A boron-interstitial doped C2N layer as a metal-free electrocatalyst for N2 fixation: a computational study

Abstract

Electrochemical reduction of the naturally abundant nitrogen (N₂) in aqueous solutions under ambient conditions is a quite promising way for ammonia (NH₃) synthesis, in which the development of highly efficient electrocatalysts is a key scientific issue. Herein, by means of extensive density functional theory (DFT) computations, we proposed that a boron-interstitial (B_int)-doped C₂N layer can act as a metal-free electrocatalyst for N₂ fixation and reduction to NH₃. Our computations revealed that the B_int-doped C₂N layer can sufficiently activate the N₂ molecule through the “acceptance-donation” process due to its significant positive charge and magnetic moment on the B dopant. In particular, the subsequent N₂ reduction reaction prefers to proceed via the enzymatic mechanism with a rather low limiting potential (−0.15 V), suggesting its superior catalytic performance for N₂ reduction. Importantly, the B_int-doped C₂N layer possesses comparable stability to the experimentally available S-doped one and thus holds great promise for experimental synthesis. Thus, by carefully controlling the doping sites, the B-doped C₂N layer can be utilized as a quite promising metal-free catalyst with high-efficiency for N₂ reduction, which may provide useful guidance for further facilitating sustainable NH₃ synthesis.